A water purifier refers to an apparatus for purifying raw water such as tap water such that the raw water is suitable for drinking. Such a water purifier is classified variously into a natural filtration scheme, a direct filtration scheme, a distillation filtration scheme, a reverse osmosis scheme and the like. In current time, examples of the most commonly used filter include a natural filtration water purifier and a direct filtration water purifier that purify water by using a filter.
Such a water purifier using a filter includes a filter and a water storage tank. In some cases, a separate heater and a separate cooling system using a refrigerant may be provided to supply cold water and hot water.